Vol 3 No. 1 July – Sept. 2008 | ISSN 1793-3609 OUTLOOKVol3 No1-Final.pdf · gold medals for the...

To spread information and knowledge and to promote collaboration in the area of Materials Research, Engineering

and Technology amongst the members of MRS-S

Vol 3 w No. 1 w July – Sept. 2008 | ISSN 1793-3609

Ø MRS-S Activities: Past, Present and Future

The Materials Research Society of Singapore (MRS-S) organized fourInternational and two National Conferences in Singapore since 2001. The bien-nial ‘International Conference on Materials for Advanced Technologies(ICMAT)’ series were held in 2001, 2003, 2005 and 2007. The biennial NationalConferences were held in 2004 and 2006. MRS-S also sponsored/supported sev-eral other conferences, workshops, symposia and public lectures. It institutedgold medals for the best outgoing students in Materials Science at the NationalUniversity of Singapore (NUS) and Nanyang Technological University (NTU).It instituted the ‘MRS Singapore Student Bursary Fund’ at the NationalUniversity of Singapore. MRS-S also instituted the ‘MRS-S Book Prize’ at the‘Republic Polytechnic’ of Singapore. This yearly Book Prize will be awarded tothe top final-year student from the ‘Diploma in Materials Science’.

To reach out to the public, MRS-S has organized number of public lecturesby Nobel Laureates and also an Astronaut.

The third ‘National Conference on Advanced Materials’, (incorporatingMRS-S and MRS-I Mumbai-Chapter Joint Indo-Singapore Meeting) was held atthe Institute of Materials Science and Engineering (IMRE), Singapore, duringFeb., 25-27, 2008. It was well-attended with 2 Keynote Talks, 60 Invited Talks,211 Posters, and 300 participants from both within Singapore and India. Ten‘Best Poster Awards’ were given away on the last day of the Conference. The listis included in this Issue.

The annual general Body Meeting (AGM) of MRS-S was held on April 9,2008 at IMRE. A new ‘Executive Committee’ was elected. The composition ofthe Committee is listed in this Issue.

ICMAT 2009 will be held during June 28-July 3, 2009 in Singapore. It willhave 21 Symposia, Plenary and Theme Lectures in addition to the Keynote,Invited, Oral talks and Poster presentations. There will also be an Exhibition ofthe products and services by the manufacturer, book and journal publishers.

The First Announcement of ICMAT 2009 is available at the website: www.mrs.org.sg

C O N T E N T SC O N T E N T SMRS-S MRS-S Activities: Past, PresentActivities: Past, Present

and Future and Future

ppage 1...age 1...

MRS-S Executive Committee MRS-S Executive Committee

ppage 2...age 2...

HighlightHighlights of previous ICMAs of previous ICMATT

ConferencesConferences

ppage 2...age 2...

HighlightHighlights of the Recents of the Recent

Literature Literature

ppage 4...age 4...

Recent BooksRecent Books

ppage 7...age 7...

Materials Education &Materials Education &

Research in SingaporeResearch in Singapore

ppage 1age 11...1...

Theme Theme Article Article

ppage 12...age 12...

Forthcoming ConferencesForthcoming Conferences


Theme Theme Articles’Articles’ Appeared inAppeared in

VVol. 2 Nos. 1-4ol. 2 Nos. 1-4


MRS-S MembershipMRS-S Membership


InvitInvitation to MRS-S Membersation to MRS-S Members


© 2008 MRS-S, Singapore. All rights reserved.

August 11, 2004 19:27 Research Publishing Services (RPS) : MRS-S e-newsletter v3n1

Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKB

estP

oste

rs:3

rdN

atio

nalC

onfe

renc

e

MRS-S Executive Committee(For 2008–2010)

PresidentB.V.R. Chowdari, NUS

Founding PresidentShih Choon Fong, NUS

Vice PresidentsLim Seh Chun, NUSFreddy Boey, NTU

SecretaryChia Ching-Kean, IMRE

Joint SecretaryFeng Yuan Ping, NUS

TreasurerDing Jun, NUSJoint Treasurer

Gregory Goh, IMREMembers

Ramam Akkipeddi, IMREPalani Balaya, NUSLiu Ai Qun, NTULiu Zishun, IHPC

Joachim S. C. Loo, NTULu Chun, NTU

Daniel Pickard, NUSS. E. Valavan, Rep Poly

Andrew S. W. Wong, IMREYang Yi-Yan, IBN

Honorary Auditors (2008–2009)Shen Zexiang, NTUTeng Jinghua, IMRE

NUS: National University of SingaporeNTU: Nanyang Technological University, SingaporeIBN: Institute of Bioengineering and Nanotechnology, SingaporeRep Poly: Republic Polytechnic, SingaporeIMRE: Institute of Materials Research & Engineering, SingaporeIHPC: Institute of High Performance Computing, Singapore

Highlights of Previous ICMAT Conferences

Year 2001: 1–6, July 2001; 16 Symposia;10 Plenary Lectures; 4 Public Lectures by NobelLaureates; 1400 delegates; 18 Best Poster Awards;36 Exhibitors.

Year 2003: 7–12, Dec., 2003; 16 Symposia;9 Plenary Lectures; 2 Public Lectures by NobelLaureates; 1500 delegates; 19 Best Poster Awards;29 Exhibitors.

Year 2005: 3–8, July 2005; 25 Symposia; 9 PlenaryLectures; 2 Theme Lectures; 3 Public Lectures byNobel Laureates; 2200 Delegates; 28 Best PosterAwards; 43 Exhibitors.

Year 2007: 1–6, July 2007; 18+6 Symposia;9 Plenary Lectures; 2 Theme Lectures; 2 PublicLectures by Nobel Laureates; 2300 Delegates; 25Best Poster Awards; 41 Exhibitors.

Highlights of Previous National Conferences

Year 2004: 6 Aug., 2004; 20 Invited Talks; 130Poster Papers; 4 Best Poster Awards.

Year 2006: 18–20, Jan., 2006; Includes the Sym-posium on ‘Physics and Mechanic of AdvancedMaterials’; 60 Invited Talks; 200 Poster Papers; 1Public Lecture; 5 Best Poster Awards.

Year 2008: 25–27, Feb., 2008. Incorporated theMRS-I Mumbai (India)-Chapter Joint Indo-Singapore Meeting; 2 Keynote Talks, 60 InvitedTalks; 211 Poster Papers; 10 Best Poster Awards.

MRS-S OUTLOOK (ISSN 1793-3609) is published quarterly by the Materials Research Society of Singapore(MRS-S), c/o Institute of Materials Research & Engineering, 3, Research Link, Singapore 117 602.Editor: G.V. Subba Rao. Disclaimer: Statements and opinions expressed in ‘MRS-S OUTLOOK’ are solely thoseof the authors, and do not reflect those of MRS-S, nor the editor and staff. Permissions: The subject matter con-tained in ‘MRS-S OUTLOOK’ can be freely reproduced for not-for-profit use by the readers; however, a word ofacknowledgement will be appreciated.

A Quarterly publication by the Materials Research Society of Singaporepage 2


MRS-S OUTLOOK Volume 3 • No.1 • July–Sept., 2008

Bes

tPos

ters

:3rd

Nat

iona

lCon

fere

nce

3rd National Conference: Best Posters

Best Poster Awards of the 3rd MRS-S National Conference,held in Singapore during February 25–27, 2008

Poster P006Title of the Paper Mesoporous — Al2O3 as an Environmentally Friendly Aldol Reaction CatalystAuthors Peng Bai, Pingping Wu, Guofeng Zhao, Zifeng Yan and George Zhao

Poster P036Title of the Paper Fabrication and Characterization of Pd Nanorods with Sacrificial Ni Segments

to Achieve Controlled NanogapsAuthors Manippady Krishna Kumar, Maria A. S. Chong, Tan Jia Xin, Tan Lee Kheng

and Gao Han

Poster P054Title of the Paper Suzuki Coupling on Diamond SurfaceAuthors Yu Lin Zhong, Anupam Midya, Zhi Kuan Chen and Kian Ping Loh

Poster P067Title of the Paper DNA Sensing by Carbon Nanotube based Field Effect TransistorsAuthors Gui Ee Ling, L. J. Li, P. S. Lee and S. G. Mhaisalkar

Poster P089Title of the Paper Ultrawide Band High Reflectivity SiO2/SiN Distributed Bragg Reflector for

Broadband Photonic DevicesAuthors X. K. Liu, C. K. Chia, M. Suryana and Y. W. Zhang

Poster P118Title of the Paper Investigation of Birefringence of Hybrid Photonic Crystal Fibers with Elliptical

Cladding Rods and Air HolesAuthors Juan Juan Hu, Yongchao Bai, Perry Ping Shum, Guobin Ren, Xia Yu,

Guanghui Wang and Chao Lu

Poster P132Title of the Paper MnO2-Carbon Nanocomposite Electrodes for SupercapacitorsAuthors Zhang Li Li and George Zhao

A Quarterly publication by the Materials Research Society of Singapore page 3


Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKH

ighl

ight

s:R

ecen

tLit

erat

ure

Poster P149Title of the Paper Current-Perpendicular-to-Plane Spin Valves with Confined Current Paths for

Ultrahigh-Density Magnetic RecordingAuthors Wang Chen Chen, Zong Baoyu, An Lihua, Luo Ping, Yeo Wee Kay, Qiu Jinjun,

Guo Zaibin and Han Guchang

Poster P168Title of the Paper Molecular Resolution Dynamic Force Microscopy of Liquid/Solid InterfacesAuthors W. Hofbauer, L. Kunardi, N. N. Gosvami and S. J. O’Shea

Poster P203Title of the Paper Indentation Study of Breast Cancer Cells Using Atomic Force MicroscopyAuthors Q. S. Li, G. Y. H. Lee and C. T. Lim

Highlights of the Recent Literature

(Contributed by the Editor)

An Updatable HolographicThree-dimensional Display

Holographic three-dimensional (3D) displays,which are static provide realistic images, mak-ing them valuable tools for applications thatrequire situational awareness, such as medi-cal, industrial and military imaging. Hologramswith moving pictures will be of great interest,and recently Tay et al. [1] reported an updat-able 3D display based on cheap, easy- to- pro-cess photorefractive polymer materials. The thin-film 3D-display device, 4 × 4 inches in size, iscapable of recording and displaying new imagesevery few minutes, can be viewed for severalhours without the need for refreshing, and canbe completely erased and updated with newimages when desired. The authors stated thattheir device showed no degradation or dielec-tric breakdown for extended periods of usage(several months) in display recording exper-iments, with hundreds of write/erase cyclesevery month at high applied voltages (9 kV)and optical intensities around 100 mW cm−2.

Reference

1. S. Tay, P.-A. Blanche, R. Voorakaranam, A. V. Tunc,W. Lin, S. Rokutanda, T. Gu, D. Flores, P. Wang,G. Li, P. St Hilaire, J. Thomas, R. A. Norwood,M. Yamamoto and N. Peyghambarian, Nature (2008)451, 694–698 (Feb., 7 Issue).

Self-Healing and ThermoreversibleRubber from Supramolecular Assembly

Rubbers exhibit enormous extensibility up toseveral hundred per cent, and have the abilityto recover their original shape and dimensionson release of stress. The elasticity of rubber isa property of macromolecules that are eithercovalently cross-linked or connected in a net-work by physical associations, ionic aggregatesor multiple hydrogen bonds. Cordier et al. [1]recently reported the design and synthesis ofmolecules that associate together to form bothchains and cross-links via hydrogen bonds.These supramolecular rubbers show recoverableextensibility up to several hundred per cent




Hig

hlig

hts:

Rec

entL

iter

atur

e

and little creep under load. In striking contrastto conventional rubbers which are made up ofmacromolecules, these supramolecular rubberswhen broken or cut, can be repaired by bringingtogether the fractured surfaces, for a minimumcontact period of 15 min, to self-heal at roomtemperature. The repaired samples were found torecuperate their enormous extensibility and thecycle of stretching, breaking and healing could berepeated many times.

The synthesis procedure is as follows: A mix-ture of fatty diacid and triacid is condensed firstwith diethylene triamine and then reacted withurea to give a mixture of oligomers equippedwith complementary hydrogen bonding groups:amidoethyl imidazolidone, di(amidoethyl) ureaand diamido tetraethyl triurea. The resultingcompound, called A, resembles a translucentglassy plastic with a glass transition temperature(Tg) of 28 ◦C, and behaves like a soft rubber. Tolower the Tg, A is plasticized with varying quan-tities of dodecane. With 11% w/w dodecane, Tgis∼ 8 ◦C and the resulting compound, called B, is anon-tacky rubber-like material. The compound Bis the one which shows the above mentioned self-healing properties.

Reference1. P. Cordier, F. Tournilhac, C. Soulie-Ziakovic and

L. Leibler, Nature (2008) 451, 977–980 (Feb., 21 Issue).

Stretchable and Foldable Silicon IntegratedCircuits

Kim et al. [1] reported a method of combiningnanoribbons of silicon with thin plastic or rubberysubstrates to produce robust, flexible, bendableand foldable integrated circuits (ICs), exhibitingvery good performance. Thus, high-performancen- and p-channel metal-oxide semiconductorfield-effect transistors (MOSFETs), complemen-tary metal oxide semiconductor (CMOS) logicgates, ring oscillators, and differential amplifiers,have been fabricated and tested, which show elec-trical properties as good as analogous systemsbuilt on conventional silicon-on-insulator (SOI)wafers.

The procedure begins with spin-casting asacrificial layer of poly(methylmethacrylate)(PMMA) (∼100 nm) followed by a thin, sub-strate layer of polyimide (PI) (∼1.2 µ m) on a Siwafer that serves as a temporary carrier. A trans-fer printing process with a poly (dimethylsilox-ane)(PDMS) stamp delivers to the surface of thePI, organized arrays of n- and p-doped Si nanorib-bons with integrated contacts, separately formedfrom n-type source wafers. Depositing and pat-terning SiO2 (∼50 nm) for gate dielectrics andinterconnect crossovers, and Cr/Au (5/145 nm)for source, drain, and gate electrodes and inter-connects yield fully integrated Si-CMOS circuits.The total thickness of Si-CMOS/PI system is ∼1.7µ m.

A notable feature of their design is that theelectronics layer lies in the neutral bending planewhich experiences almost no strain, even whenthe overall device is very bent. The authors alsoperformed three-dimensional analytical and com-putational modeling of the mechanics and theelectronic behaviors of these integrated circuits.

Reference1. D.-H. Kim, J. Ahn, W. M. Choi, H.-S. Kim, T.-H. Kim,

J. Song, Y. Y. Huang, Z. Liu, C. Lu and J. A. Rogers,Science (2008) 320, 507–511 (April, 25 Issue).

Bulk Superconductivity at 38 K in aMolecular System

The occurrence of superconductivity inalkali-metal- or alkaline earth metal-doped C60fullerides, has been known since 1991. The high-est transition temperature, Tc achieved wasaround 33 K. Recently, Ganin et al. [1] reported asuccessful synthesis of highly-crystalline Cs3C60,employing cesium metal and fullerene (C60) andmethylamine as the solvent medium, and foundthat the phase with the body centered cubic(bcc) structure of the A15-type (similar to theintermetallic compound, Nb3Sn- a well-knownsuperconductor with a Tc of 18 K), exhibits bulksuperconductivity, under pressure (in the range,7.9–11.6kbar), with an onset temperature as highas 38 K. The shielding fraction, an estimate of



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKH

ighl

ight

s:R

ecen

tLit

erat

ure

the amount of superconducting phase in a mix-ture of phases, was found to be as high as 67%.

Reference1. A. Y. Ganin, Y. Takabayashi, Y. Z. Khimyak,

S. Margadonna, A. Tamai, M. J. Rosseinsky and K.Prassides, Nature Mater., (2008) 7, 367–371 (MayIssue).

Superconductivity at 43 K in an Iron-basedLayered Compound LaO1−xFxFeAs

The group of Hosono [1] in Japan, recentlyreported that the compound, La (O1−xFx)FeAs(x∼0.1) shows superconductivity at 43 K whensubjected to a pressure of 4 Gpa (∼ 40 kbars).At ambient pressure, they found that it becomessuperconducting below ∼26 K, and the resultswere published in Feb., 2008. The above grouphas been studying the physical properties of theiso-structural series of compounds, LnOTMPn(Ln=Y or rare-earth metal; TM= transition metal;Pn=a group-V element, ‘pnicogen’) for the pasttwo years, and found some of them to showsuperconductivity, with the transition tempera-ture, Tc at ∼3–5 K (see, MRS-S OUTLOOK, 2 (2),39 (2007).

The work of Takahashi et al. [1] has cap-tivated the attention of researchers worldwide,and as Cho [2], in his ‘News Focus’ pointed out,preprints are now available which claim to havefound a Tc of 55 K in the compound where La inLa(O1−xFx) FeAs is replaced by Sm, another rareearth metal.

Thus, a new era of high temperature supercon-ductors (HTSC) has begun. Till now, the mixedcopper oxides (for example, YBCO, BiSCCO etc.)have been the only examples of HTSC, whichshow a Tc above 40 K.

The system of compounds, LnOTMPn havebeen first synthesized and characterized by thegroup of Jeitschko in Germany many years ago.They possess the so-called ‘filled’ PbFCl structure.They are layer-type compounds with a tetragonalstructure, with the TM-ion in a tetrahedral coordi-nation. They usually exhibit a metallic-type con-duction. The crucial innovation by Takahashi et al.[1] is in doping the parent compound, LaOFeAswith electrons by a partial substitution with flu-orine (F) at the O-site, resulting in a substantialincrease in Tc to ∼26 K.

Both theorists and experimentalists havealready started making a comparison betweenthe two series of HTSC in terms of the struc-ture, physical properties, Tc, mechanism of super-conductivity etc. The most important differ-ence perhaps is the nature of carriers, ‘holes’in Cu-oxide HTSC vs. electrons in LnOTMPn.Researchers may now be tempted to have are-look at the ‘electron-doped’ Cu-oxides like,(Nd2−xCex)CuO4which show a Tc ∼20–25 K.

Highly toxic nature of arsenic, and the cum-bersome procedure necessary to make the aboveLnOTMPn, including La(O1−xFx) FeAs, meanthat not many laboratories in the world willspend time and effort to pursue the new systemof HTSC, unlike the unprecedented worldwideeffort twenty years ago on the Cu-oxide HTSC.Thus, there is an urgent need to develop facile andprecursor synthetic methods for the LnOTMPn,especially those with Pn=N, P and Sb.

References

1. H. Takahashi, K. Igawa, K. Arii, Y. Kamihara,M. Hirano and H. Hosono, Nature (2008) 453,376–378 (May, 15 Issue).

2. A. Cho, Science (2008) 320, 870–871 (May, 16 Issue).




Rec

entB

ooks

and

Rev

iew

Art

icle

s

Recent Books and Review Articlesin the Area of Materials Science, Engineering and Technology

(Contributed by the Editor)

Books

• Nanotechnology-Enabled Sensors. Edited byKourosh Kalantar-zadeh and Benjamin Fry,Springer, New York, 2007, Hardback: 503 pp.,illus. $129. ISBN 9780387324739.

• Applied Computational Materials Modeling:Theory, Simulation and Experiment. Editedby Guillermo Bozzolo, Ronald D. Noebeand Phillip B. Abel, Springer, New York,2007, Hardback: 507 pp., illus. $129.ISBN 9780387231174.

• Rugged Free Energy Landscapes: Common Com-putational Approaches to Spin Glasses, StructuralGlasses and Biological Macromolecules. Editedby W. Janke, Springer, Berlin, 2007. Hardback:422 pp., illus. $99. ISBN 9783540740254.

• Self Healing Materials: An Alternative Approachto 20 Centuries of Materials Science. Editedby S. van der Zwaag. Springer, Dordrecht,Netherlands, 2007. Hardback: 395 pp., illus.$169. ISBN 9781402062490.

• Semiconductor Lasers: Stability, Instability andChaos. 2nd ed. Edited by Junji Ohtsubo,Springer, Berlin, 2007. Hardback: 494 pp., illus.$189. ISBN 9783540726470.

• Smart Structures: Blurring the Distinction Betweenthe Living and the Nonliving. Edited by VinodK. Wadhawan. Oxford University Press,Oxford, 2007. Hardback: 363 pp., illus. $110.ISBN 9780199229178.

• Structure of Materials: An Introduction to Crys-tallography, Diffraction, and Symmetry. Editedby Marc De Graef and Michael E. McHenry.Cambridge University Press, Cambridge,2007. Hardback: 876 pp., illus. $95.ISBN 9780521651516.

• Transmission Electron Microscopy and Diffractom-etry of Materials. 3rd ed. Edited by Brent Fultzand James Howe, Springer, Berlin, 2007. Hard-back: 778 pp., illus. $119. ISBN 9783540738855.

• Tribology of Diamond-Like Carbon Films: Funda-mentals and Applications. Edited by ChristopheDonnet and Ali Erdemir. Springer, NewYork, 2007. Hardback: 670 pp., illus. $119.ISBN 9780387302645.

• Plenty of Room for Biology at the Bottom. An Intro-duction to Bionanotechnology. Edited by EhudGazit. Imperial College Press, London 2007.183 pp., hardcover $ 62.00. ISBN 978-1-86094-677-6.

For a review, see, Angew. Chem. Int. Ed., 47 (2),236–237 (2008)

• Synthesis, Properties, and Applications of OxideNanomaterials. Edited by Jose A. Rodriguez andMarcos Fernadez-Garcia. John Wiley & Sons,Hoboken, NJ 2007, xi + 717 pp., hardcover,$135. ISBN 978-0-471-72405-6.For a review, see, Adv. Mater.,20 (1), 208 (2008).

• Bio-inorganic Hybrid Nanomaterials: Strate-gies, Syntheses, Characterization and Applica-tions. Edited by Ruiz-Hitzky, Eduardo, Ariga,Katsuhiko and Lvov, Yuri M. Wiley-VCH,



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKR

ecen

tBoo

ksan

dR

evie

wA

rtic

les

Weinheim, 2007. Hardcover. 503 pp., 149.- EUR.ISBN 978-3-527-31718-9.

• Advances in Electronic Ceramics. Edited byRandall, Clive. Wiley-VCH, Weinheim,2007. Hardcover. 258 pp., 62.90 EUR.ISBN 978-0-470-19639-7.

• Biomedical Nanostructures. Edited by Gonsalves,Kenneth, Halberstadt, Craig, Laurencin, CatoT and Nair Lakshmi. Wiley-VCH, Weinheim,2007. Hardcover. 508 pp., 99.90 EUR.ISBN 978-0-471-92552-1.

• Nanostructured Materials and Nanotechnol-ogy. Edited by Mathur, Sanjay. Wiley-VCH,Weinheim, 2007. Hardcover. 196 pp., 62.90EUR. ISBN 978-0-470-19637-3.

• Reliability of MEMS. Edited by Tabata,Osamu and Tsuchiya, Toshiyuki. Wiley-VCH,Weinheim, 2007. Hardcover., 304 pp., 159.-EUR. ISBN 978-3-527-31494-2.

• Photonic Crystals-Molding the Flow of Light.2nd Ed. Edited by John D. Joannopoulos etal. Princeton University Press, Princeton, NJ,2008. Hardback. 304 pp., illus. $75, £44.95.ISBN 9780691124568.

• Fuel Cell Electronics Packaging. Edited byKen Kuang and Keith Easler. Springer,New York, 2007, Hardback: 258 pp., illus. $129.ISBN 9780387473239.

• Functional Nanostructures: Processing, Character-ization, and Applications. Edited by Sudipta Seal.Springer, New York, 2007. Hardback: 607 pp.,illus. $129. ISBN 9780387354637.

• Flux Pinning and AC Loss Studies on YBCOCoated Conductors. Edited by M. Parans Paran-thaman and Venkat Selvamanickam. Nova Sci-ence, Hauppauge, NY, 2007. Hardback: 421 pp.,

illus. $129. ISBN 9781600216923.

• High Energy Density Materials. Edited byT. M. Klapotke. Springer, Berlin, 2007. Hard-back: 298 pp., illus. $269. ISBN 9783540722014.

• Physics of Ferroelectrics: A Modern Perspective.Edited by Karin M. Rabe, Charles H. Ahn,and Jean-Marc Triscone. Springer, Berlin,2007. Hardback: 400 pp., illus. $199.ISBN 9783540345909.

• Thin Film Optical Coatings for Effective SolarEnergy Utilization: APCVD Spectrally SelectiveSurfaces and Energy Control Coatings. Editedby K. A. Gesheva. Nova Science, Hauppauge,NY, 2007. Hardback: 307 pp., illus. $129.ISBN 9781600216435.

• Semiconductor Radiation Detectors. By GerhardLutz. Springer, Berlin, 2007. Paperback: 365 pp.,illus. $79.95. ISBN 9783540716785.

• Processing and Fabrication of Advanced Materi-als XVI (PFAM XVI). Edited by M. Gupta1,T. S. Srivatsan2 and Sanjay K. Thakur3

(1Department of Mechanical Engineering,National University of Singapore, Singapore.2Department of Mechanical Engineering, TheUniversity of Akron, USA. 3Electronics andSafety, Delphi Automotive Systems, Singa-pore.). Research Publishing Services, Sin-gapore. Dec., 2007, 706 pp., Hardbound,ISBN: 978-981-05-9650-7. Price: US$138 / 96(includes cd-rom).




Rec

entB

ooks

and

Rev

iew

Art

icle

s

PFAM XVI contains collection of papers frompracticing engineers, technologists, researchscientists and academicians from 10 coun-tries. 57 accepted papers are included in thisbound volume. This inter-disciplinary pub-lication provides together the state-of-the-art developments on all aspects related tothe processing and fabrication of advancedmaterials spanning the entire spectrum of met-als and alloys, intermetallics, ceramics, ceramicmatrix composites, metal-matrix composites,intermetallic-matrix composites, advancedpolymers, polymer-matrix composites, semi-conductor materials, and surface and high-temperature coatings. Topics Covered are:Advanced Processing Methods; AdvancedComposites; Advanced Metallic Materials;Energy Storage Materials; Functional Materi-als; Simulation Studies; Surface Coatings.

Review Articles

• The Larger Acenes: Versatile Organic Semicon-ductors, By J. E. Anthony, Angew. Chem. Int. Ed.,47 (3), 452–483 (2008).

AbstractAcenes, the group of homologous organiccompounds, naphthalene, anthracene, tetracene,pentacene etc., have long been the subject ofintense study because of the unique electronicproperties associated with their π-bond topology.Recent reports of impressive semiconductor prop-erties of larger homologues have re-invigoratedresearch in this field, leading to new methods fortheir synthesis, functionalization, and purifica-tion, as well as for fabricating organic electroniccomponents. Studies performed on high-purityacene single crystals revealed their intrinsic elec-tronic properties and provide useful benchmarksfor thin film device research. New approachesto add functionality were developed to improvethe processability of these materials in solu-tion. These new functionalization strategies haverecently allowed the synthesis of acenes largerthan pentacene, which have hitherto been largely

unavailable and poorly studied, as well as investi-gation of their associated structure/property rela-tionships. 355 References.

• Magnetoelectric Laminate Composites: AnOverview, By J. Zhai, Z. Xing, S. Dong, J. Li andD. Viehland, J. Amer. Ceram. Soc., 91 (2) 351–358(2008).

AbstractThe magnetoelectric (ME) effect is defined by theelectric field (E) induced under application of amagnetic field (H); or vice versa, by the magneticinduction (B) induced under application of anelectric field (E). Since the turn of the millennium,giant ME effects have been found in laminatedcomposites of piezoelectric and magnetostrictivelayers. Compared with ME single phase and two-phase particulate composites, laminated compos-ites have much higher ME coefficients and arealso readily fabricated.

Here, the authors present a overview of thebrief history of ME laminates, discussing some ofthe important advancements in material couples,laminate configurations, and operational modesthat have allowed for dramatic enhancements inthe ME voltage and charge coefficients. 53 Refer-ences.

• Doped Nanocrystals, By D. J. Norris, A. L. Efrosand S. C. Erwin, Science, 319, 1776–1779 (2008)(28 March Issue).

AbstractThe critical role that dopants play in bulk semi-conductor devices has stimulated research onthe properties and the potential applications ofsemiconductor nanocrystals, or colloidal quan-tum dots, doped with intentional impurities. Itis known that doping enhances the properties ofnanocrystals by providing another means to con-trol their remarkable electronic, optical, transport,and magnetic properties.

The authors review the advances made inthe chemical synthesis of doped nanocrystals,in the theoretical understanding of the funda-mental mechanisms that control doping, and in



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKR

ecen

tBoo

ksan

dR

evie

wA

rtic

les

the creation of highly conducting nanocrystallinefilms. Because impurities can be used to alterthe properties of nanoscale materials in desirableand controllable ways, doped nanocrystals canaddress key problems in applications from solarcells to bio-imaging. 40 References.

• Nanomaterials for Rechargeable LithiumBatteries, By P. G. Bruce, B. Scrosati andJ.-M. Tarascon, Angew. Chem. Int. Ed., 47 (16),2930–2946 (2008).

AbstractRechargeable lithium ion batteries (LIBs) havebeen the present-day choice for applications inportable electronic devices like, cell phones, lap-top computers, video camcorders etc. Future gen-erations of LIBs and those using lithium metalas anodes are required to operate high-powerportable tools, store electricity from renewablesources, and as a vital component in new elec-tric vehicles (EVs) and hybrid EVs. Efforts are alsobeing made to improve the performance of all-solid-state LIBs for integration in to, for exam-ple, microelectromechanical devices (MEMS). Toachieve the future challenges of energy stor-age, new materials chemistry, and especially newnanomaterials chemistry, is essential.

The authors review some of the recent sci-entific advances in nanomaterials, and especiallyin nanostructured materials, for LIBs. They pointout that ultimate expression of the nanoscale inrechargeable lithium batteries is the formationof 3D nanoarchitectured cells, in which pillaredanodes and cathodes are interdigitated. 111 Ref-erences.

• Organic ferroelectrics, By S. Horiuchi and Y.Tokura, Nature Mater., 7 (5), 357–366 (2008).

AbstractFerroelectricity is the phenomenon by which thespontaneous electrical polarization in a substancecan be reversed by the application of an electricfield. A large number and wide variety of inor-ganic, organic and organo-metallic compounds

which are electronically-insulating, exhibit fer-roelectricity below a transition temperature, TC.They find extensive practical applications in awide variety of devices.

In this article, the authors review advances inthe synthesis of new organic materials based onnon-covalent molecules formed by two or morecomponents, with promising ferroelectric proper-ties near room temperature, using design prin-ciples in analogy to inorganic compounds. Theyexpressed the hope that ‘this article will stimu-late both academic and technological interests inorganic ferroelectrics and innovative advances inthe ever-growing field of organic electronics’. 79References.

• Mesoporous Carbon Materials: Synthesis andModification, By C. Liang, Z. Li and S. Dai,Angew. Chem. Int. Ed., 47 (20), 3696–3717 (2008).

AbstractPorous carbon materials are of interest in manyapplications due to their high surface areaand physicochemical properties. Recent break-throughs in the preparation of other porous mate-rials have resulted in the development of methodsfor the preparation of mesoporous carbon materi-als with extremely high surface areas and orderedmesostructures, with potential applications ascatalysts, separation media, and advanced elec-tronic materials in many scientific disciplines.Current synthesis methods can be categorized aseither hard-template or soft-template (more cor-rectly, self-assembled templates) methods.

In this review, the authors present anoverview of the template-assisted synthesis andchemical modification (surface functionalization)of the mesoporous carbon materials. 181 Refer-ences.

• Aurivillius ceramics: Bi4 Ti3O12 -based piezo-electrics, By T. Jardiel, A. C. Caballero and M.Villegas, J. Ceram. Soc. Japan, 116 (1352), 511–518(2008).

AbstractBi4Ti3O12-based ferroelectrics, which are alsopiezoelectrics represent the ‘Aurivillius oxides




Rec

entB

ooks

and

Rev

iew

Art

icle

s

family’, and have attracted renewed interest dur-ing the last few years due to their ‘lead-free’nature and promising properties as high tempera-ture piezoelectric materials. This review examines

how the development of these materials has takenplace from their discovery at the end of the 1940’sand the existing knowledge about their process-ing and properties. 114 References.

Materials Education & Research in Singapore

There are two Universities and several Research Institutes in Singapore involved in teaching,research and development in the broad area of Materials Science, Engineering and Technology.These are listed below along with the Websites and provide information on the available coursesand opportunities for undergraduate, graduate and post doctoral research. They also entertainqueries regarding openings for Research Scientists and Faculty positions.

National University of Singapore: www.nus.edu.sg

Nanyang Technological University: www.ntu.edu.sg

Institute of Materials Research and Engineering (IMRE): www.imre.a-star.edu.sg

Institute of Microelectronics (IME): www.ime.a-star.edu.sg

Data Storage Institute: www.dsi.a-star.edu.sg

Institute of Chemical & Engineering Sciences: www.ices.a-star.edu.sg

Institute of High Performance Computing: www.ihpc.a-star.edu.sg

Singapore Institute of Manufacturing Technology: www.SIMTech.a-star.edu.sg

Institute of Bioengineering and Nanotechnology (IBN): www.ibn.a-star.edu.sg

MRS-S welcomes you to the ICMAT 2009 Conference Website

http://www.mrs.org.sg/icmat2009



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKT

hem

eA

rtic

le

Theme Article

From Applied Science to Commercial Application — Synchrotron Radiation as a BroadR&D Platform: Part IIIa

H. O. Moser1,2, K. Banas1, M. Cholewa1, C. Z. Diao1, X. Y. Gao2, L. K. Jian1, S. M. P. Kalaiselvi1, Z. J. Li1,G. Liu1, T. Liu2, S. M. Maniam1, A. T. S. Wee2, P. Yang1, Y. Adam Yuan3,4

1 Singapore Synchrotron Light Source, National University of Singapore, Singapore2 Department of Physics, National University of Singapore, Singapore3 Department of Biological Sciences, National University of Singapore, Singapore4 Temasek Life Sciences Laboratory, National University of Singapore and Nanyang Technological University, Singapore

4 Thin Film Characterization by X-rayReflectometry

4.1 Introduction

Systems of thin layers are common to manyfields including bioengineering, data storage,photonics, and semiconductor electronics. X-rayreflectometry (XRR) is to determine the layerparameters by measuring reflection intensity orpower from the layered system. Under grazingincidence, X-rays are totally reflected by mat-ter as the refractive index is <1. When theangle of incidence is increased, there will bea material-specific cut off angle arising abovewhich the X-rays penetrate into the material. Theintensity of the specularly reflected beam drasti-cally decreases. Simultaneously, the interferenceof rays reflected from various depths into the lay-ered system leads to fringes as a function of theincidence angle. Fig. 32 shows schematically whatparameters of layers can be obtained by XRR.

The XRR data evaluation is based on amodel by Parratt [24]. Applying Fresnel formu-lae to multiple layers, the model provides thelayer parameters mentioned above. XRR is apowerful tool to characterize film for the layerthickness, density/porosity and surface/interfaceroughness. Such parameters can be determinedonly separately by other means such as TEM(transmission electron microscopy), SIMS (sec-ondary ion mass spectroscopy) or AFM (atomicforce microscopy) under certain resolution limits

and not always non-destructively. The traditionalweight/volume method can still be adopted todetermine the density of the film, but it fails forthicknesses down to several tens of nano-meters[25]. XRR enables such determination of the thick-ness and density of a layer within a relative errorof 1/1000 and 1/100, respectively, while the sur-face roughness can generally be derived within anerror of about 0.1 nm. Moreover, XRR is unique inproviding interface roughness which can hardlybe determined by any other means.

XRR at SSLS has been available since theX-ray demonstration and development (XDD)beam line was commissioned in August 2003 [15].Using synchrotron radiation, the measurementof XRR enables a broader dynamical range andhigher angular resolution of reflectivity. More-over, the photon energy (or wavelength) of theincident X-ray beam can be tuned to any desiredvalue within the available spectral range, thusmaking some layers or elements sensitive toreflectivity, and enabling the use of anomalousscattering effects. We have successfully workedon the characterization of films consisting of poly-mers, semi-conductors and heavy metals. Someselected results will be presented in this article[25–29].

4.2 Experimental and basic principle

The layout for XRR measurement at XDD beam-line is shown in Fig. 19. The diffractometer isthe Huber 4-circle system 90000–0216/0 (Fig. 20),

aThis is a six-Part article. Parts I and II appeared in the previous Issues. Parts IV to VI will appear in subsequent issues–Editor.




The

me

Art

icle

Substrate

σ

σ

σF ilm

θ θ

��

��

Fig. 32. Schematic of a film on a substrate. X-rays are incident on and reflected from the surface. The reflectivity is R(θ)=I1/I0,I0 and I1being the incident and reflected X-ray intensities, respectively. Layer parameters such as thickness, density and sur-face/interface roughness can be obtained from the reflectivity.

with high precision 0.0001◦ step size for theomega (ω) and two-theta (2θ) circles. ForXRR measurements, no analyzer is used, butentrance and detector slits with 0.9 and 1 mmwidth, respectively (adjustable). The distancefrom entrance slit to sample centre is 688 mmand that from sample centre to detector slit680 mm (adjustable). The storage ring, Helios 2,runs at 700 MeV, with a typically stored elec-tron beam current of 300 mA. The energy of theX-ray photons is selected by a Si (111) channel-cut monochromator (CCM). The photon beam isconfined to 0.90 mm width vertically and 3.50 mmhorizontally by the collimating mirror and slitsystem. Such a set-up yields an X-ray beam typ-ically with about 0.01◦ in divergence at 8.048 keV.Typical counting time is 5 seconds for every step.

A formula describing the reflection behaviorof a layered system is given below in dynamicalapproach for an N layer system on a substrate [24,27, 30]

Rj−1,j =rj−1,j + Rj,j+1 . e−2ik j.dj

1+ rj−1,j . Rj,j+1 . e−2ik j.dj. (1)

where j denotes the jth interface between layer j−1and j (layer j-1=0 is the air and j = N the sub-strate. So jth=1st interface is the surface), Rj−1,j

the amplitude of the wave reflected from thejth interface, rj−1,jthe Fresnel coefficient of X-rayreflection from the jth interface, k j the normal-component of X-ray wave vector in layer j, anddj the thickness of layer j.

Repeatedly using the recursive formula (1)from the substrate (RN,N+1 = 0, there is only trans-mitted wave in the substrate) up to the surface,R0,1, the experimentally accessible reflectivity canbe expressed as

R(θ) = |R0,1|2. (2)

In above formulae, Snell’s law and nj, theindices of refraction at every interface j, are hid-den in the Fresnel coefficient rj−1,j [26,29,30] and

nj = 1− (δj + iβ j); (3)

δj =Nare2π

λ2 ·∑k

ρkAk

(

Zk + f ′k)

; (4)

β j =Nare2π

λ2 ·∑k

ρkAk

f ′′k =µjλ

4π; (5)




hem

eA

rtic

le

Lu2O3

(Lu2O3)xS iy

�

S i- s ub s tr a te

0 2 4 6 8 1010-8

10-6

10-4

10-2

100

��

��

��

�θ��

Fig. 33. Top) XRR data of Lu2O3 thin film annealed at 800◦C and its best simulation, 8.048 keV. The film is split into two sub-layers as shown schematically in the in-set at upper-right corner; Bottom) An HRTEM photo of a similar film grown at the samecondition but annealed at 900 ◦C [31]. There are two different contrasts in the original layer (marked Lu2O3). That is an indicationof the silicate layer formed and original Lu2O3 layer became thinner.

The critical angle θc for total external reflectionis given by

ϑc =

√

2(

δ2j + β2

j

)1/2≈

√

2δj , (6)

where Na is the Avogadro constant, rethe classicalelectron radius, λ the wavelength of the X-raysin vacuum, ρk the mass density of the kth con-stituent (ρk = wkρo, wk is the weight fraction andρo the mass density for complex materials), Akthe atomic mass, Zkthe atomic number, f ′

k and f ′′k

the real and imaginary parts of atomic anoma-lous scattering factors respectively for all of thekth constituent and µj the linear absorption coeffi-cient of the layer j. The critical angles are appar-ently connected with the densities of the layersand the atomic anomalous scattering factors. Bychanging the photon energy towards the absorp-tion edges, we may achieve a higher sensitivity inreflectivity for certain elements contained in thelayer to determine the layer parameters with bet-ter precision, due to the change in the scatteringfactors.




The

me

Art

icleAn equivalent transfer matrix theory describ-

ing XRR behaviour can be found in [30].

4.3 Results and Discussion

Recently, some films have successfully beeninvestigated using XRR at the XDD beamline. Inthis section, several films made of polymers, met-als, electric materials and oxides are shown astypical applications of XRR to characterization offilms. Through the thickness determination, thelayers can be confirmed to be present. The porousor crystalline status of the layer can be deducedfrom the density change. Besides, an example ofanomalous scattering effect on XRR is shown.

4.3.1 Thickness determination – confirminglayered structures

4.3.1.1 Lu2O3 filmsLu2O3 thin films have been deposited on n-type (100) Si substrates using pulsed laserdeposition. High-resolution transmission electronmicroscopy (HRTEM) observation shows that theLu2O3 film has amorphous structure and theinterface with Si substrate has suffered inter-diffusion, even after a high annealing tempera-ture up to 900 ◦C in oxygen ambient (lower partof Fig. 33). A well shaped C-V characteristic and

k-values of 15.95 and 11.59 with the equivalentoxide thickness (EOT) of 1.10 and 1.68 nm wereobtained for the 600 and 900 ◦C samples respec-tively. The amorphous Lu2O3 film annealed at 900◦C in oxygen ambient showed a low leakage cur-rent density of 1.0 × 10−4 A/cm2 at +1 V biasfor ∼5 nm thick Lu2O3 thin film after the postannealing process in oxygen ambient. Althoughthere is such an inter-diffused silicate layer whichlowers the overall k value and increases EOTvalue, Lu2O3 is still a potentially good candidateto replace SiO2 as a gate dielectric material [31].

XRR data shown in the upper part ofFig. 33 confirm the results obtained from HRTEM.Deposited Lu2O3 layer was split into two sub-layers: silicate and original one with densitiesof 5.2 and 8.6 g/cm3respectively, due to inter-diffusion between Lu2O3 layer and Si-substrate.Rest of layer parameters can be found in Table 3.

4.3.1.2 ITO filmITO film is used for LED materials and is oftenfound to form sub-layers. The reflectivity dataand its best fit for an ITO film are shown inFig. 34. The layer parameters are listed in Table 4.Here, 3 sub-layers, i.e. ITO-1 and ITO-2 and itsinter-diffused mixture with substrate SiO2 are dis-covered.

Table 3. XRR simulated results for Lu2O3 thin film, 8.048 keV.

Sample Thickness (nm) Roughness (nm) Density (g/cm3)

Annealed Lu2O3 2.2±0.1 0. 65±0.08 8.6±0.5at 800◦C Lu2O3+Si 2.1±0.1 0.50±0.08 5.2±0.5

Si-Substrate - 0.1±0.1 2.33 (fixed)

Table 4. Layer parameters for the indium-tin-oxide (ITO, In2−xSnxO3−2x) determinedfrom reflectivity of 8.048 keV X-rays.


Al 150 > 4.2 2.6±0.1ITO-1 3.1±0.6 1.9±0.3 7.51±0.09

ITO film-3 ITO-2 112.9±0.4 0.1 7.59±0.08SiO2/ ITO 19.9±0.4 0.71±0.07 3.4±0.2Glass-Substrate − 0.8±0.2 2.4




hem

eA

rtic

le

0 2 4

1 0-6

1 0-4

1 0-2

1 00

��

��

��

�θ��

Al-layer

IT O -1

IT O -2

S iO 2/IT O

G las s -

s u b s trate

Fig. 34. X-ray reflectivity of an indium-tin-oxide (ITO, In2−xSnxO3−2x) film on a cover-glass plate, capped with an Al layer.8.048 keV X-rays were used. The layer parameters are obtained from the best fit as listed in Table 4. Inset in the upper-right corner:layer scheme in the film. Three sub-layers, ITO-1 and ITO-2, and a mixture layer SiO2/ ITO are shown by X-ray reflectivity.

Layer thicknesses larger than 2 nm candirectly be determined or confirmed, as revealedin the first example above. Combined with othermeans, even smaller thicknesses can be obtained,for example, delta-layers [26]. Upper limit mightbe up to 1 µm depending on layer quality andthe parallelism in the incident X-ray beam. UsingXDD, we have successfully determined a thick-ness of 400 nm for GaAs epi-layers. In the nextsection, an example of a SiLK layer with thicknessof 330 nm is shown.

4.3.2 Layer evolution — density change andporosity

Density in a layer draws attention as it deter-mines the element ingredients, porosities, crys-talline status and other physical properties of thefilms, either during growth or after various treat-ments. In this section, density changes in severalfilms under different treatments are shown.

4.3.2.1 SiLK filmsDielectric materials with low dielectric constantsk are introduced in semiconductor manufactur-ing in order to reduce resistance-capacitance (RC)delay. Spin-on low k materials have attracted

much attention because of their process simplic-ity [26].

P-SiLK films under study were spin-coateddirectly on silicon wafers, cured, and treated withvarious plasmas, such as O2, H2/N2, O2/N2,CH2F2/Ar and CF4/O2. Details about the treat-ment can be found in a previous paper [26].These plasma-treated films were investigatedusing XRR. The results show that there are tran-sition layers 6-7 nm thick existing between sub-strates and SiLK layers, most probably the mix-tures of native oxide layers and initially grownlayers. XRR results confirm that the density ofthe p-SiLK films remains unchanged after variousplasma treatments, referred to the untreated sam-ple run 1.

But surface roughening occurs during thetreatments, accompanied by a thickness decrease.Such roughening is more severe for oxygenplasma treatment. Hence it is reasonable toconclude that oxidation of the surface plays amajor role in surface roughness change. Forexample, in sample run 5, surface roughness is aslarge as 2.1 ± 0.2 nm. The experimental data andsimulation are shown in Fig. 35. AFM observa-tions (not shown here) reveal close values of thesurface roughness to those obtained by XRR.




The

me

Art

icle

0.0 0.2 0.4 0.6 0.8 1.0

10-5

10-4

10-3

10-2

10-1

100

��

��

��

��χ��

!�

��"��#��$

θ%��

0.1 0.2

10-1

100

0.6 0.7 0.8 0.9

10-4

Fig. 35. Reflectivity and simulation for SiLK run 5 (treated in CH2F2/Ar plasma). The insets show finer details at lower andhigher grazing angles in the simulation. X-ray photon energy: 8.048 keV. Layer thickness is worked out as 330 ±1 nm and density0.96 ± 0.01 g/cm3. The porosity is then calculated as 10% if bulk SiLK density is 1.07 g/cm3.

4.3.2.2 Parylene filmThe density of a spin-coated parylene film hasbeen determined by XRR with a good precisionof about 1%. The results are as shown in Fig. 36.The density of so thin a layer cannot be obtainedusing traditional methods as described in [25].

4.3.2.3 Density change of Ge2Sb2Te5 after heatingGe2Sb2Te5 is an optical storage material. Layerdensity will change during the storage process(heating). Such change will offer some insight intothe material phase transition. Fig. 37 shows reflec-tivity behavior of as-grown layer (amorphous)and annealed one. Layer parameters are listed inTable 5.

For as-grown sample, the density is lowerthan 5.56 g/cm3, as it is amorphous and henceporous; after annealing of the sample at 250 ◦C,the density changed to 6.10 g/cm3. It is an indica-tion that the layer has crystallized. The oxide lay-ers of about 5 nm thickness were formed after thesamples were taken to the air.

4.3.3 Anomalous scattering effect in reflectivity

In formulae (3) to (5) which influence the reflectiv-ity, we have contributions from the atomic num-ber Zk and the real and imaginary parts f ′

k and f ′′k

of the correction to the atomic scattering factor fk.If the atomic scattering factor is written as

fk = f 0k + f ′k + i f ′′k (7)

and if we measure at a small scattering angle,i.e. near the forward direction, we obtain

fk = Zk + f ′k + i f ′′k . (8)

Normally, fk turns to be Zk as the correction isclose to zero. If the photon energy is chosen nearthe absorption edges of the elements, the correc-tions f ′k and f ′′k are large enough to produce someeffect on the reflectivity as expected from the for-mulae. For a nitrogen atom, there is nearly no dif-ference in the real part of the scattering factor,i.e. 7.07e and 7.03e at 5.000 and 8.048 keV respec-tively, whereas there is a three times difference inits imaginary parts, i.e. 0.051e and 0.018e at 5.000and 8.048 keV respectively.

An experimental example of such an effecton the reflectivity is shown with a poly-(styrene-block-2-vinylpyridine) diblock copolymer (PS-b-P2VP) film template on a gold evaporated Siwafer. XRR measured using conventional X-raysof 8.048 keV (CuKα1) has not shown any sign




hem

eA

rtic

le

0.0 0.5 1.0 1.5 2.0

10-5

10-4

10-3

10-2

10-1

100

��

�� χ��

��

�� !��"��#��

��$� ��"��

��%� ��$� ��

��&�� "��' ��

(�$�� ) �

θ��

Fig. 36. Reflectivity and simulation of a parylene film. The results are shown in the in-set. X-ray photon energy: 8.048 keV.

0 1 2 3 4 510-7

10-5

10-3

10-1

101

��

��

��

��

��

��

�

θ��

1.2 1.5 1.8 2.1

10-3

Fig. 37. Reflectivity of Ge2Sb2Te5films, measured and simulated. The inset shows details of an oscillation in the reflectivity ofannealed sample, which enables the determination of layer thickness for Ge2Sb2Te5 layer, whereas no oscillation was measuredand hence the thickness can not be obtained for amorphous sample. X-ray photon energy: 8.048 keV.

of a PS-b-P2VP template, but only the parame-ters for Au layer, as seen in the upper part ofFig. 38. In contrast, using 5.000 keV X-rays, thetemplate layer was clearly revealed and layerparameters could be determined, yielding a thick-ness of about 18 nm and density of 0.8 g/cm3. Theresults are shown in Table 6, Figs. 38 and 39, the

latter being an enlarged part of the measurementsat smaller momentum transfer q (small incidenceangle), where a critical momentum transfer qc(≈0.035 A−1) and oscillations appear that are dif-ferent from those for the Au layer. It is a clear andthe most direct indication of the existence of thePS-b-P2VP template.




The

me

Art

icleTable 5. Layer parameters of Ge2Sb2Te5 films from reflectivity of 8.048 keV X-rays.


250◦C, X2 = 1.93×10−3 Ge2Sb2Te5-oxide 5.4±0.2 1.5±0.1 4.57±0.09Ge2Sb2Te5 196±2 0.2±0.1 6.10±0.05Si-substrate − 1.2 2.4 (fixed)

Amorphous(as-grown), X2 = 3.22×10−3 Ge2Sb2Te5-oxide 4.6±0.1 1.5±0.1 4.39±0.08Ge2Sb2Te5 ^ 0.0±0.1 5.56±0.08Si-substrate − 1.2 2.4 (fixed)

��

��

0.0 0.1 0.2 0.3

10-7

10-5

10-3

10-1

101

��

� �!"

#��$��%��& ��

Fig. 38. X-ray reflectivities of a PS-b-P2VP template on a gold evaporated Si wafer, along with the best fit for 5.000 keV X-rays.The inset shows a schematic of the layer structure. XRR using conventional X-rays of 8.048 keV can not show any sign of thetemplate existence, but only the Au layer and Cr layer (the latter not shown in the inset). In contrast, XRR using 5.000 keV yieldsmost of layer parameters as listed in Table 6.

Table 6. Layer parameters of the PS-b-P2VP template on a gold evaporated Si wafer determinedfrom reflectivity of 5.000 keV X-rays.


PS-b-P2VP 18±3 >1. 0.8±0.1PS-b-P2VP template Au 42.8±0.3 1.16±0.06 17.1±0.7

Cr 1.5 1.1±0.1 6.9±0.4Si-Substrate − 0.7±0.1 2.39




hem

eA

rtic

le

0.00 0.03 0.06 0.09

1 00

��

��

��

��

��!�"�#��

Fig. 39. X-ray reflectivities of a PS-b-P2VP template on a gold evaporated Si wafer, enlarged from the smaller q part of Fig. 38,along with the best fit for 5.000 keV X-rays. Note that different critical momentum transfers qc are shown for the Au layer and thePS-b-P2VP template respectively, which are corresponding to a combined effect of all the layers in the film, but mostly from thetemplate and Au layers. This critical momentum transfer (≈0.035 A−1) for the template can only be seen in this reflectivity with5.000 keV X-rays, whereas it can hardly be seen with 8.000 keV X-rays. The appearance of this critical momentum transfer is aclear and the most direct indication of the existence of the PS-b-P2VP template.

4.4 Conclusions

Films can be characterized using XRR at SSLS.Due to a higher flux and lower divergence of asynchrotron radiation X-ray beam, a dynamicalrange up to several 109 can be achieved inXRR, which can make the characterization moreeffective. The method is non-destructive and theresults are naturally averaged over the range ofX-ray spot on the sample. In favourable cases, itcan be applied in situ.

When a layer composed of lighter elementsis included in the film, the conventional methodmay not work. However, if lower energy X-raysare used unique to synchrotron radiation, thelighter layer can be revealed without doubt, asshown in the PS-b-P2VP template. Furthermore,if the X-ray energy is selected near the absorp-tion edge, the effect even achieves its maximum.

References

24. L. G. Parratt, Phys. Rev. 95, 359–369 (1954).25. Hong Liang Huang, Yongan Xu and Hong Yee

Low, Polymer, 46, 5949–5955 (2005).26. P. Yang, D. Lu, B. Ramana Murthy and H.

O. Moser, Surface and Coatings Technology, 198,133–137 (2005).

27. X. Li, S. Tian, P. Yang, D. H. Kim and W. Knoll,LANGMUIR 21, 9393–9397 (2005).

28. P. Yang, D. Lu, R. Kumar and H. O. Moser, Nucl.Instr. and Meth. in Phys. Res. B 238, 310–313 (2005).

29. H. O. Moser, M. Bahou, B. D. F. Casse, L. K. Jian,Ping Yang, X. Y. Gao, A. T. S. Wee, CrystallographyReports 51, S170–S182 (2006).

30. P. Yang, Singapore J. of Phys. 16, 79–85 (2000).31. P. Darmawan, P. S. Lee, Y. Setiawan, J. C. Lai,

P. Yang, Thermal stability of rare-earth based ultra-thin Lu2O3 for high-k dielectrics, J. Vac. Sci. Technol.B 25, 1203–1206(2007).




Con

fere

nces

:For

thco

min

g

Forthcoming ConferencesThe 4th International Conference on Technological Advances of Thin Films &

Surface Coatings (ThinFilms2008)a in conjunction withThe 1st International Conference on nanoManufacturing (nanoMan2008)b

14 – 16, July, 2008, Singapore

For further information and Abstract submissionsee:www.thinfilms-Singapore.org; www.tju.edu.cn/nanoMan2008:

aChair: Sam Zhang; Co-Chair: Frank F. S. ShieubChair: Fengzhou Fang; Co-Chair: Jack Luo

IUMRS - ICEM 2008(International Conference on Electronic Materials 2008)

28 July to 1 August, 2008, Sydney, Australia

IUMRS - ICEM 2008 is Sponsored by the International Union of Materials Research Societies and Orga-nized by the Australian Materials Research Society.

Organizers: Rob Elliman, ANU, AustraliaJohn O’Connor, University of Newcastle, Australia.

The following Symposia will be held under the Topics.Properties and Characterisation:Symp. J: Synchrotron Radiation, Symp. K: Materials Modelling and Design for Property Enhancement;Symp.L: Ion Beam Processing and Characterisation; Symp. M: Mechanical Properties of Electronic Mate-rials and Thin Films; Symp. N: Nanoscale Characterisation using Electron Microscopy.

Thin Films, Surfaces and Functional Materials for Specific Applications:Symp. O: Amorphous Materials; Symp. P: Production, Processing and Characterisation of High kDielectrics; Symp.Q: Polymeric Materials and Organic Semiconductors; Symp. R: Superconductors, Elec-tronic and Magnetic Materials.

Symp. S: Materials EducationThis Symposium S invites presentations of ideas, achievements and progress, by educators developingnew curricula, new teaching resources, new teaching strategies, and creative interactive programs. Italso offers special presentations to assist educators in their professional careers. Educators for all levels(K-12, undergraduate, graduate, continuing education, and community outreach) are urged to partici-pate.

Symposium Topics include

New elements of curriculum, e.g. nanotechnology, biomaterials, eco-materials.Novel approaches to teaching and learning. Adapting for the cyber-generation.Integration of software/textbooks/labs/lectures/classes.Modular learning resources, self-paced courses, online courses.



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKC

onfe

renc

es:F

orth

com

ing

New software for course management and assessment.Laboratory modules and facilities.Undergraduate research programs.Community outreach.Reconciling tertiary and K-12 curricula.Technical update resources for educators.

Invited Speakers include

Bill CALLISTER, Univ. of UtahAndrew WEE, National Univ. of SingaporePeter GREEN, Univ. of MichiganH.-U. HABERMEIER, Max-Planck Institute — StuttgartDavid BAHR, Washington State Univ.Alan CROSKY and BelindaALLEN, Univ. of New South WalesDoug PEROVIC, Univ. of TorontoKathie CHEN, California Polytechnic InstituteG. Slade CARGILL, Lehigh Univ.Laura BARTOLO, Kent State Univ.Noel RUTTER, Cambridge Univ.Grant NORTON, Washington State Univ.Joe SHAPTER, Flinders Univ.

Proceedings PublicationProceedings will be published in the peer-reviewed ”Journal of Materials Education”.Abstracts: Abstract submission is now open. An abstract of a maximum of 3000 characters.

Web address: http://www.aumrs.com.au/ICEM-08/http://www.aumrs.com.au/ICEM%2D08/Abstracts/Submission/

Contact address:Laura Walmsley, Personal Assistant to the Director (Professor Jim Williams),Research School of Physical Sciences & EngineeringThe Australian National University, Canberra ACT 0200, Australia.E-mail: [email protected]

AsiaNANO 2008Biopolis, Singapore, November 3–7, 2008

The 2008 Asian Conference on Nanoscience and Nanotechnology (AsiaNANO 2008) will be held inBiopolis, Singapore, on November 3–7, 2008. The main objective of the conference is to provide a stagefor Asian scientists working in the field of nanoscience and nanotechnology to network and communi-cate their latest research findings. Asian countries have been greatly contributing to the rapid progressin nanotechnology research.

This is the fourth conference in the AsiaNANO series. The first was held in Tokyo in 2002, the sec-ond in Beijing in 2004, and third in Pusan, South Korea in 2006. This conference series has become animportant academic symposium for nanoscience research in Asia, creating effective networking among




The

me

Art

iclethe Asian scientists, institutions and companies, and promoting the inter-countries and interdisciplinary

collaborations in nanotechnology.Singapore has been the scene of many exciting developments in scientific research, including in

the fields of nanoscience and nanotechnology. The venue of the conference is Biopolis, a purpose-builtbiomedical research hub where researchers from the public and private sectors are co-located. Situatedin the south-western part of Singapore, the Biopolis is within walking distance of the Buona Vista MRTStation and is near both the National University of Singapore and the National University Hospital. Wecordially invite you to participate in the AsiaNANO 2008 conference in Singapore.

Selected papers will also be published in a special issue of the International Journal of Nanoscience.The scientific program includes plenary, invited and contributed talks and poster sessions, in the

following symposia:

1. Carbon nanotubes and related nanomaterials2. Graphene: Materials and devices3. Nanomagnetics, spintronics and multiferroics4. Nanobioscience and nanobiotechnology5. Functional Nanoassembly: nanoparticles, quantum dots, nanoarchitectures and self-assembled

architectures6. Multi-paradigm simulation at the nano-scale: methodology and applications7. Nanofabrication: nanoimprinting, nanolithography and related techniques

The official language for written and printed materials, as well as for presentation and discussion, isEnglish.

Web site:http://www.asianano2008.org/Important Dates:Abstract Submission Deadline: 1 July 2008Notification of Acceptance: 1 August 2008

Contact address:AsiaNano 2008 Secretariat, c/o Integrated Meetings Specialist Pte LtdBlock 998 Toa Payoh North, #07-18 Singapore 318993.Tel: (65) 6356 4727; Fax: (65) 6356 7471; Email: [email protected]

Theme Articles’ Appeared in ‘MRS-S OUTLOOK’, Vol. 2 (Nos. 1–4)

• From Applied Science to Commercial Application — Synchrotron Radiation as a Broad R&D Platform: Part I”,By H. O. Moser1, K. Banas1, B. D. F. Casse1,5, A. Chen1, M. Cholewa1,6, C. Z. Diao1, X. Y. Gao2,S. P. Heussler1, L. K. Jian1, S. M. P. Kalaiselvi1, Z. J. Li1, G. Liu1, T. Liu2, Shahrain bin Mahmood1,S. K. Maniam1, A. T. S. Wee2, P. Yang1, Y. Adam Yuan3,4, MRS-S OUTLOOK, 2 (1) 11–24 (2007).1Singapore Synchrotron Light Source, National University of Singapore, Singapore.2Department of Physics, National University of Singapore, Singapore.3Department of Biological Sciences, National University of Singapore, Singapore.4Temasek Life Sciences Laboratory, National University of Singapore and Nanyang TechnologicalUniversity, Singapore.5Electronic Materials Research Institute, Northeastern University, Boston, USA6 ANKA, Forschungszentrum Karlsruhe, Germany.




hem

eA

rtic

le Abstract: In this Part I of theme article are illustrated the capabilities and scope of synchrotron radia-tion applications using the example of the Singapore Synchrotron Light Source (SSLS) with selectedsections on micro/nanofabrication.Applications in the areas of X-ray diffraction, reflectometry, absorption fine structure spectroscopy,photoemission spectroscopy, phase contrast imaging, and the development of new sources will bedescribed and discussed in the near future.

• “From Applied Science to Commercial Application — Synchrotron Radiation as a Broad R&D Platform:Part II”, By H. O. Moser1, K. Banas1, M. Cholewa1, C. Z. Diao1, X.Y. Gao2, L. K. Jian1,S. M. P. Kalaiselvi1, Z. J. Li1, G. Liu1, T. Liu2, S. K. Maniam1, A. T. S. Wee2, P. Yang1, Y. Adam Yuan3,4,MRS-S OUTLOOK, 2 (2) 42–52 (2007).1Singapore Synchrotron Light Source, National University of Singapore, Singapore.2Department of Physics, National University of Singapore, Singapore.3Department of Biological Sciences, National University of Singapore, Singapore.4Temasek Life Sciences Laboratory, National University of Singapore and Nanyang TechnologicalUniversity, Singapore.

Abstract: Applications of Synchrotron radiation in the following areas of materials science are dis-cussed with illustrative examples: High resolution X-ray diffractometry; Rietveld refinement of theX-ray powder data; Structure of La10−xNax(SiO4)6O3−x from resonant diffraction; Super-structure in(GaIn)P2epi-layer; Mapping in reciprocal space — epi-layer inclination, Mapping in reciprocal space –clarification of crystal structure, and X-ray topography — surface inclusion in Si wafer.

• “Indium Phosphide Based MEMS for Tunable Devices”, By Ramam Akkipeddi*, J. Arokiaraj*, S. Vickneshand S. Mithilesh, MRS-S OUTLOOK, 2 (3) 66-82(2008).

*Institute of Materials Research and Engineering, Agency for Science Technology and Research(A*STAR), 3, Research Link, Singapore 117602.

Abstract: The introduction part discusses the motivation and importance of III-V based MEMS struc-tures in WDM applications. The Finite Element Analysis (FEA) modeling of various architectures fora membrane structure is then discussed. The simulation work encompasses a new filter design and aninvestigation of electro-mechanical response. The consequent evolution of a criterion while trying tooptimize the dimensions of a filter (based on mechanical/optical considerations) has led to four filterdesigns. The branched beam type novel filter design has a lower compliance as compared to otherfilter designs, and is the one used for fabricating into a Electro-static (E-S) actuator. The fabricationschemes, their optimization and release of InP membranes using an improvised freeze-dry techniqueis presented. Side-wall protection for the InP membrane structures was introduced by depositing SiO2layer and etching it selectively over the beam regions, thus avoiding the undercutting for the supportregions. The fabricated actuators were characterized under DC and quasi-static conditions, with adeflection of about 350 nm, pull in voltage of 7 volts, and with a response time of about 100 µsec.

• “From Inorganic Compounds to Inorganic Materials”, By Lu Tian and Jagadese J. Vittal, MRS-S OUT-LOOK, 2 (4) 96-113(2008).

Department of Chemistry, National University of Singapore, Singapore 117543.E-mail: [email protected]




Mem

bers

hipAbstract: Inorganic materials can be prepared by conventional method, such as direct reaction

of the elements,1,2 solid-state metathesis reactions,3 and solution phase metathetical reactions ofMClx (x = 4, M = Ti, Mo; x = 5, M = Nb) with Li2S4 These conventional synthetic technologies havethe potential environmental, safety and health hazards when handling some toxic reagents5 Theyalso suffer from stoichiometry control problems, impurity incorporation, and unwanted side reac-tions. Moreover, the high temperatures involved require harsh reaction conditions which are not easyto achieve.

Another promising method to prepare inorganic materials is to use single molecular precursors.In this review, we have shown that it is possible to design metal complexes, i.e., single molecules

for making inorganic materials in various forms. Most of the inorganic compounds discussed in thispaper can be easily synthesized in large quantities with high yield. They are air stable and can beused as single-source precursor to generate the corresponding inorganic materials without involv-ing in toxic reagents. The inorganic materials obtained have varied from bulk, thin films to NCs.Successful control of the size and shape of inorganic materials makes further advancement in thesolid-state properties. Especially, the low temperature synthesis of ternary metal chalcogenides NCsor deposition of thin films has opened the door for improving the performance of solar cells. Success-ful demonstration of lanthanide chalcogenide nanomaterials synthesis is also indicating the possiblenovel materials for future LCD display materials. The single-molecular precursor chemistry has nowemerged as a new area in the synthetic inorganic chemistry and can be termed as ‘synthesis for pur-pose’. Synthetic inorganic chemists are expected to play more important roles towards the develop-ment of second generation nanomaterials in the future.

The above articles can be accessed through the website: http://www.mrs.org.sg/outlook/

MRS-S MembershipReaders are invited to become members of the Materials Research Society of Singapore (MRS-S).

Professional Membership is open to any person engaged in activities associated with materials science,engineering and technology.

Student Membership is open to any bonafide student of a tertiary institution genuinely interested inthe practice of materials science, engineering and technology.

Corporate Membership is open to any organisation, government or private, commercial or otherwise,that is in any way engaged in any activities that deal with any aspect of material science, engineeringand technology. A Corporate Membership is entitled to nominate two of its employees as its officialrepresentatives and to change its nominees from time to time provided the Committee has no objectionto any such nomination.

Annual Subscription Fee:Professional Membership: S$50Student Membership: S$5Corporate Membership: S$500

For details and application form, please visit: www.mrs.org.sg



Volume 3 • No.1 • July–Sept., 2008 MRS-S OUTLOOKIn

vita

tion INVITATION

MRS-S members are welcome tocontribute to ‘MRS-S OUTLOOK’

• To suggest topics and prospective author(s) for ‘thematic’ articles pertaining tothe areas of materials science, engineering and technology. These will be ofgeneral interest to the students, teachers as well as active researchers. Thesecan be 10–15 pages (A4-size, single spaced) with figures, tables and selectreferences.

• To contribute reports on the recently held conferences and information on theforthcoming conferences.

• To contribute ‘Highlights from Recent Literature’ in the areas of materi-als science, engineering and technology. These must pertain to the years2006–2008, and be of general interest to non-specialists, students, teachers aswell as active researchers. Each ‘Highlight’ must not exceed 250–300 words,including reference(s). Contributing author(s) and e-mail address(es) will beincluded under each ‘Highlight’.

• To contribute information about the recent awards and distinctions conferredon the MRS-S members.

• To contribute ‘Letters to the Editor’. They may be edited for brevity, clarity andavailable space, and the author(s) will be informed.

Information on the above aspects may be communicated to the Editor:

Dr. G.V. Subba RaoE-mail: [email protected]

The Editorial Board of ‘MRS-S OUTLOOK’ reserves the right to include or not any of the submitted contributions.

Design & Typeset by Research Publishing ServicesE-mail:[email protected]


Vol 3 No. 1 July – Sept. 2008 | ISSN 1793-3609 OUTLOOKVol3 No1-Final.pdf · gold medals for the...

Documents

Transcript of Vol 3 No. 1 July – Sept. 2008 | ISSN 1793-3609 OUTLOOKVol3 No1-Final.pdf · gold medals for the...